The Pine Time is a $27 smart watch that runs open source firmware, making it an ideal candidate for AI-assisted development. Inspired by @steveruizok's Tweet about hacking ESP32 devices with Claude, I pulled my Pine Time out of storage to explore what AI coding assistants could accomplish.

I aimed to build a custom watch face, drawing inspiration from @levelsio's custom Casio watch face for Apple Watch. Using Open Code with open weights models like Kimi K3, Deep Seek v4 Pro, and Flash, I cloned the Infini Sim repository and got a build working quickly on Ubuntu.

I challenged the AI to replicate a watch face from a photo, starting with existing Infini Time code. While the initial result was rough with overlapping text elements, it served as a solid foundation. Through iterative feedback and isolated tasks, I refined each element individually.

To optimize performance, I created a fullscreen background image with static elements, only programming the dynamic parts. Though the 240x240 image takes 10 minutes to transfer via Bluetooth and 1-2 seconds to refresh, it works acceptably for a prototype. The code is available on GitHub, complete with an AGENTS.md file summarizing lessons learned.